use RSA_PSS_SALTLEN_DIGEST constant

Reviewed-by: NRichard Levitte <levitte@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2301)

ssl/statem/statem_clnt.c

@@ -2024,7 +2024,8 @@ MSG_PROCESS_RETURN tls_process_key_exchange(SSL *s, PACKET *pkt)
         if (ispss) {
             if (EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) <= 0
                        /* -1 here means set saltlen to the digest len */
-                    || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1) <= 0) {
+                    || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx,
+                                                RSA_PSS_SALTLEN_DIGEST) <= 0) {
                 al = SSL_AD_INTERNAL_ERROR;
                 SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_EVP_LIB);
                 goto err;

ssl/statem/statem_lib.c

@@ -231,8 +231,8 @@ int tls_construct_cert_verify(SSL *s, WPACKET *pkt)
 
     if (ispss) {
         if (EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) <= 0
-                   /* -1 here means set saltlen to the digest len */
-                || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1) <= 0) {
+            || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx,
+                                                RSA_PSS_SALTLEN_DIGEST) <= 0) {
             SSLerr(SSL_F_TLS_CONSTRUCT_CERT_VERIFY, ERR_R_EVP_LIB);
             goto err;
         }
@@ -404,8 +404,8 @@ MSG_PROCESS_RETURN tls_process_cert_verify(SSL *s, PACKET *pkt)
 
     if (ispss) {
         if (EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) <= 0
-                   /* -1 here means set saltlen to the digest len */
-                || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1) <= 0) {
+            || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx,
+                                                RSA_PSS_SALTLEN_DIGEST) <= 0) {
             SSLerr(SSL_F_TLS_PROCESS_CERT_VERIFY, ERR_R_EVP_LIB);
             goto f_err;
         }

ssl/statem/statem_srvr.c

@@ -2274,8 +2274,7 @@ int tls_construct_server_key_exchange(SSL *s, WPACKET *pkt)
             if (ispss) {
                 if (EVP_PKEY_CTX_set_rsa_padding(pctx,
                                                  RSA_PKCS1_PSS_PADDING) <= 0
-                           /* -1 here means set saltlen to the digest len */
-                        || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1) <= 0) {
+                    || EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, RSA_PSS_SALTLEN_DIGEST) <= 0) {
                     SSLerr(SSL_F_TLS_CONSTRUCT_SERVER_KEY_EXCHANGE,
                            ERR_R_EVP_LIB);
                     goto f_err;